Electric oven



M y 22. 1934. M. F. H. GOUVERNEUR ,959,358

' ELECTRIC OVEN Filed April 18, 1932 ATTORNEY Patented May 22, 1934 UNITED STATES PATENT OFFICE 1 Claim.

The invention relates to a novel form of electric oven, especially adapted for dental work and the like, and has for its object to provide a relatively simple but highly efficient oven, all of the parts of which, except the heating coil and its accessories, may be made from fire-clay, porcelain or the like by any of the approved methods of making pottery or earthenware articles, the several elements of the structure being separable and renewable, so that, in addition to initial low cost, any damaged or impaired elements may be replaced at correspondingly low cost without the need of special tools.

The invention is illustrated in the accompanying drawing, in Which:--

Fig. 1 is a sectional elevation of the complete oven.

Fig. 2 is a plan view in half section.

Referring to the drawing, 1 indicates a generally disk-shaped base provided on its marginal edge with spaced steps 2, 2' and having supporting feet 1 on its under face.

Mounted on the base are concentric annular walls 3 and 4, the lower edges of which rest on the step sections 2, 2, said annular walls preferably being separated by an air space, which materially reduces the waste of heat by radiation from the walls. If desired, the outer wall 2 may be cemented to the base, as indicated at 3'.

Concentrically disposed within the inner wall 4 and supported on the base by means of spaced feet is a generally cup-shaped shell 5 constituting the housing for the heating coil, said shell being provided with an annular shoulder near its top and having formed in its interior wall surface a helical groove 6 adapted to receive and retain the successive convolutions of an electric heating coil 7, the ends of which are adapted to be connected to binding posts 9 and 12 mounted in openings in the base 1, the binding post 9 preferably being centrally located with respect to the base 1 and the shell 5 and passing through registering openings in the bottom of the shell 5 and the base 1, and, therefore, constituting a bolt which securely locks the shell to the base, the opening in the bottom of the shell 5 above the head of the binding post being closed by a suitable refractory plug.

Mounted concentrically within the shell 5 of the heating unit is a muffle or sagger 15, which is generally cylindrical or cup-shaped and provided at its rim with a peripheral flange l5 engageable with the shoulder or ledge 5' on the interior of the shell to suspend the muille concentrically with respect to the shell 5 and the heating coil '7. If

desired, the muflle may be provided with holes or openings in its wall to receive the ends of a spring bail or handle, as indicated by dotted lines in Fig. 1, to facilitate the removal of the mufile from the shell. The muflle is provided with a diskshaped cover 17 resting on the top of the flange 15 and provided with a central vent opening.

The oven is also provided with a removable cover 20 dished on its inner face and having an annular rib 21 adapted to engage the upper edge of the inner wall section 4.

As stated, all of the elements of the oven, except the heating coil and the binding post terminals associated therewith, are made of fire-clay, porcelain or other highly refractory ceramic material and only the normally exposed surfaces of the base 1, the outer shell 3 and cover 20 need be finished with a suitable glaze or enamel, thereby not only avoiding the labor and expense of compIetely glazing all of the elements, but eliminating the danger of the glazing or enamel melting under the high heat of operation, which would have the disastrous effect of causing the several elements of the oven to be cemented together by the glaze, when the latter cooled.

While the oven, as a whole, and its component parts are of rugged construction sufficient to withstand the wear and tear of continued use without impairment, the several elements are so constructed that, if any of the parts become damaged, they may be readily replaced at slight cost.

What I claim is:

An electric oven, comprising a base having marginal shoulders about is periphery, spaced inner and outer annular walls and a cup-shaped shell resting on the base, said shell having a shoulder about its rim and a helical groove encircling its inner wall surface, a heating coil mounted in said groove, binding post terminals for said coil, one of which terminals serves as a bolt for locking the shell to the base, a cup-shaped muffle having an upper marginal flange engaging the shoulder on the shell, a cover for the muflle, and an outer cover for the oven.

MINOR F. H. GOUVERNEUR. 

